USB flash storage devices have become a popular way of people to share files with each other. It is common for one to give their USB storage device to someone else and ask him/her to write a file into the storage device. One may also put one or more files on their USB storage device and give the storage device to someone else so that the other person can copy the file off the storage device. Storage sizes on USB storage media has been growing at a rapid pace and it is common to have USB flash storage devices that are over a giga byte. USB hard disk storage media which are a bit larger than USB flash storage devices can also be used for similar file exchange purposes and these easily are of the order of a 100 GB. Given these large capacities one may have several files on their USB storage media.
Usually when one plugs in a USB storage device into a PC the PC has full access to all of the storage on the storage device and can read or write all of it. When person A gives his storage device to person B, he/she is vulnerable to person B reading or modifying content that person A did not intend. Even if the two people exchanging the storage devices trust each other, it is possible that the machines used in the process may be infected with malicious software and may steal information without the knowledge of the parties concerned. Malicious software may also erase contents of the USB storage device.
There are finger-print enabled USB storage media that have two partitions; an open partition that is readable/writable by all and a private partition that is completely hidden until a valid fingerprint is provided. If a valid fingerprint is provided the private partition is fully accessible.
While such a storage device can be used to address some of these issues, by keeping private information in the protected partition and shared information in the open partition. However, the size of the public partition is fixed when the storage device is initialized and cannot be changed without loss of data later. Also data stored in the public partition is vulnerable. Therefore, there is a need for a method and mechanism that overcomes the aforementioned shortcomings.